Today, we are going to see another common and interesting SQL interview question, what is the difference between SQL, T-SQL, and PL/SQL? It is also one of the most common doubts among SQL beginners. It's common for programmers to think that why there are many types of SQL languages, why not just single SQL across DB? etc. Well, let's first understand the difference between SQL, T-SQL, and PL/SQL, and then we will understand the need for these dialects. SQL is standard for querying, inserting, and modifying data in a relational database. It is categorized into DDL and DML and is powerful enough to create database objects e.g. table, view, stored procedure, and can perform CRUD operation (SELECT, INSERT, UPDATE, and DELETE) query.